What was found
FLIGHT CREW NOTICED "HOT' ODOR, SHORTLY AFTERWARD LAVATORY SMOKE DETECTOR BEGAN SOUNDING. NO SMOKE WAS OBSERVED BY CABIN CREW, ONLY HAZE. CABIN REPORTED CONDITIONS IMPROVED BY LANDING. RETURNED TO FIELD. LANDING UNEVENTFUL. PERFORMED FIM TASK 71-00-00-810-817 (SMOKE OR OILY ODOR MIST IN CABIN OR FLIGHT COMPARTMENT) COMPLYING WITH ENGINE PURGE RUNS, ENGINE BOROSCOPES, ECS PURGE RUNS. ALL RUNS WENT SUCCESSFUL WITH NO SIGNS OF SMOKE IN CABIN OR COCKPIT. FOUND ECS FAULT CODE FOR L HP SOV VALVE REPLACED HP SHUTOFF VALVE FILTER RT, LT DEFUSER PIPE O-RINGS WORN. BOROSCOPES DID NOT FIND ANY EVIDENCE OF LEAKING OIL. NO OTHER DEFECTS NOTED ACFT, OK FOR RETURN TO SERVICE.